My temp guage wasn't reading above 1/4 of the way so I replaced the sender. I also figured while I'm there I should replace the thermostat as well. (stant superstat) Put everything back together and ran the truck. It would heat up to about 3/4 on the guage and stay there. Just for kicks I started feeling hoses and the lower radiator hose is cold! After about 30 mins of driving it's still cold. Did I get a bad T-stat right out of the box?

 

The lower hose will be cooler. The hotter coolant from the engine enters the top of the radiator and is cooled as it travels down to the lower hose, where it goes the the H2O pump.

 

That is true, but I have gotten a bad stat right out of the box, just as I just did the other day with a rebuilt starter. My temp guage never goes beyond the 1/4 mark. My dad's 77 f150 never went past the 1/4 mark either. I would try another stat. Granted it (the water)does come in an filter down through the radiator, but the bottom hose should have some warmth to it too.

 

You can test your tstat by putting it in a pan of water, and set it on the stove with a meat thermometer. wait until it opens, and check the temp. Yes many tstats don't work right when new. I check them all before putting them in. Good luck.

 

Interesting, i never thought about doing that. this isnt my thread but thanks!

 

Just about everything you cared to know about thermostats...

http://performanceunlimited.com/illu...ermostats.html

 

Old trick that I learned back in the 70s when I almost burned up an engine because of a failed thermostat my uncle told me about that to see if it was the thermostat or some other problem (since I was just convinced it couldn't be that since I had just replaced it and being a teenager I KNOW it's good) we tried it and even at a rolling boil hot as we could get the pan it wouldn't open. Bought a new 180deg put it in the same pan and it began to open at 170, installed it and problem solved. Done that ever since for that very reason of it's a heck of a lot easier to check before install then do the install twice.

 

I have heard of that but never tried it. I have had one or two bad thermostats over the years I think I will do that from now on. Nothing more aggravating than doing the same work twice. As I found out this week with a rebuilt starter, GRRRRrrrrrrrrrr,………

 

Oh, another thermostat tip, ditch the RTV, it does not belong on that gasket. Use some indian head, or gasket maker, a VERY THIN coat. Most dummys have a big fat bead smooshing out, that will eventually break off, and jam your thermostat closed. Been there and done that.

Friend: Hey Tony, why does it sound like is smoking a bong??"
Me: What do you mean?
Friend: I just walked by your car, its making a loud bubbling noise.

I go over and investigate, sure enough, it sounds like a 2 year old is blowing milk bubbles in the glass. Upon further investigation the thermostat I put in 2 years ago had failed because it had the RTV break loose partially while the thermostat was open, and it closed on it, making it stick. The bead was only 1/16 of an inch, but that was enough.

 

well...took the t-stat out, tested it and its ok. Think I got a bad sender. Gonna put a mechanical guage on it to see whats up. I stuck a candy thermometer in the radiator and it read about 160*. We'll find out in a couple of hours whats really going on.

 

Bad Sender!!! Truck runs at 175* on the mechanical guage. Thanks for all the input!

 

Glad to hear it and thanks for posting the result (it's nice to have the answer posted so if someone else comes across this they can see what worked.)

 

Congrats on tracking it down.

 

175 degrees might be a little low. I always heard temps. on these trucks should be around 195-200 or so. Correct me if I'm wrong though.

 

Cool one thanks, Beavis. :)
Been wanting that graph in a thread about thermostats. :)

Ut wrote:
"Here's the stock replacement:
FlowKooler

That's the one to get.
...and Smokey Yunick would agree too. ;)

The higher operating temperature is good for gas mileage.
The 160*F thermostat is bad for your oil and your gas mileage.

A 180*F thermostat won't keep your engine from overheating.

Why a 180*F anyway?

Butthead in AZ